Such a dosing device is known from EP 12 95 646 A1. The known dosing device has a medium reservoir on which is placed a manually actuatable pumping means. The pumping means is provided with a pumping chamber, whose volume can be modified by a thrust piston. With the pumping chamber is associated an inlet valve and an outlet valve, the latter being held in a spring-loaded manner in the closed position. The inlet valve is in the form of a slide valve, which by means of a dosing stroke is held in a dosing channel in a sealing position and therefore in a closed position. Facing the medium reservoir, to the dosing channel and therefore the inlet valve is connected an inlet area, which widens in a stepped manner relative to the dosing channel. In its closed position the slide valve moves from above through the dosing channel until it passes over the stepped shoulder on moving into the inlet area and in this way opens the pumping chamber to the medium reservoir.
One object of the invention is to provide a dosing device of the aforementioned type, which permits an improved dosing operation.
This object is achieved in that the inlet area is provided with flow profilings. Thus, on opening the slide valve there is an improved flow characteristic for the medium flowing out of the medium reservoir from the dosing channel to the inlet area, so that there is an improved filling and consequently a more precise dosing for the dosing device. Unlike in the prior art where the transition between the dosing channel and the inlet area is formed by a circumferential annular step, the transition between inlet area and dosing channel as a result of the flow profilings of the inlet area is now such that there is an improved flow transfer. The flow pro-filings are preferably in the form of a profiled annular wall.
In a development of the invention the flow profilings are oriented in a longitudinal direction of the dosing stroke. Preferably a corresponding longitudinal profiling is formed by several longitudinal grooves, which extend in a uniformly distributed manner parallel to a pumping axis over the inlet area circumference. As a function of the medium introduced and desired inlet characteristic, said longitudinal grooves can be made wider or narrower. The depth of the longitudinal grooves preferably corresponds to the radius difference between the radius of the dosing device portion connecting to the inlet area towards the medium reservoir and the radius of the dosing channel.
In a further development of the invention the inlet area and dosing channel are provided on separate components, which is very advantageous from the manufacturing standpoint. As a result the dosing devices can be manufactured very precisely with relatively small dimensions. As a result of the bipartite nature, a particularly accurate opening characteristic for the slide valve can be obtained.
In a further development of the invention the components are joined together in coaxially interengaging manner and the components are so profiled on their facing circumferential surfaces that between the latter is formed at least one gas flow capillary tube between axially facing front edges of the circumferential surfaces. This ensures that a desired venting or ventilating can take place.
In a further development of the invention the at least one gas flow capillary tube is at one end open to the environment and at its other end into a medium reservoir, and on the end facing said medium reservoir is provided a filter unit. This makes it possible to ventilate the medium reservoir without bringing about a contamination of the medium by the ambient air.
The invention also relates to a dosing device for fluids having a manually actuatable pumping means, as well as with a dosing opening from which the fluid passes out of the dosing device, the dosing opening being connected by at least one fluid guide path to the pumping means and with the dosing opening is associated an outlet valve opening as a function of the pressure in the fluid guide path, the dosing opening having at least one axially sealing valve seat and in which the outlet valve comprises a sealing stem cooperating with the valve seat.
EP 12 95 646 A1 discloses a dosing device in which the outlet valve comprises a cylindrical sealing stem, which cooperates with a both axially and radially acting valve seat in the vicinity of a dosing opening of the dosing device.
A further object of the invention is to provide a dosing device of the aforementioned type, which has an improved spray characteristic.
This object is solved in that the valve seat has a shell portion radially enveloping the sealing stem, that an annulus is provided coaxially around the shell portion and that the sealing stem is surrounded by a labyrinth rim, which projects into the annulus in such a way that there are labyrinth-like flow guide paths to the dosing opening. Particularly in the case of a dosing opening constructed as a spray nozzle, this leads to advantages with respect to the spray characteristic, whilst a more precise dosing is also obtained. The invention solution is particularly suitable for liquid media used in the pharmaceutical or cosmetics sectors. The labyrinth rim is shaped integrally onto the outlet valve and coaxially and spacedly surrounds the sealing stem preferably oriented concentrically to a pumping axis of the pumping means.
In a development of the invention there is an outflow area with flow profilings upstream of the dosing opening in the outflow direction, which leads to an improved outflow characteristic in the vicinity of the dosing opening.
In a further development of the invention the sealing stem and shell portion are so mutually cylindrically constructed in a coaxially corresponding manner that additionally a radial sealing seat can be obtained, which leads to an improved opening and closing of the outlet valve.
In a further development of the invention the annulus is constructed as a circular annular groove and the labyrinth rim as a circular annular web, which has a smaller cross-section than the free cross-section of the annular groove. In a further development in the closed position of the outlet valve the adjacent surfaces of the labyrinth rim are spaced from one another. This ensures that also in the closed position of the outlet valve the labyrinth-like flow guide paths within the dosing device and therefore within the pumping chamber are completely filled with liquid medium. The fluid flow deflection directly upstream of the outlet from the dosing opening permits a particularly advantageous discharge characteristic and preferably an improved spray characteristic.
In a further development of the invention the labyrinth rim has an at least substantially rectangular cross-section. The labyrinth rim is preferably circumferentially circular. The term at least substantially rectangular cross-section more particularly means that the labyrinth rim is at least partly formed by substantially rectangular edges.
In a further development of the invention the annulus has an at least substantially rectangular cross-section. Preferably the contour of said cross-section is adapted to the outer contour of the labyrinth rim.
In a further development of the invention the outer circumference of the labyrinth rim is conically bevelled. In a further development the annulus has a conically tapered wall. Preferably the conical surfaces of the labyrinth rim and the annulus are oriented parallel to one another.